Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-37624526

RESUMO

The large-conductance Ca2+-activated K+ (BK) channel is widely expressed in the pulmonary blood vessels and plays a significant role in regulating pulmonary vascular tonus. It opens under membrane depolarization, increased intracellular Ca+2 concentration, and chronic hypoxia, resulting in massive K+ efflux, membrane hyperpolarization, decreased L-type Ca+2 channel opening, and smooth muscle relaxation. Several reports have demonstrated an association between BK channel dysfunction and pulmonary hypertension (PH) development. Decreased BK channel subunit expression and impaired regulation by paracrine hormones result in decreased BK channel opening, increased pulmonary vascular resistance, and pulmonary arterial pressure being the cornerstone of PH. The resulting right ventricular pressure overload ultimately leads to ventricular remodeling and failure. Therefore, it is unsurprising that the BK channel has arisen as a potential target for treating PH. Recently, a series of selective, synthetic BK channel agonists have proven effective in attenuating the pathophysiological progression of PH without adverse effects in animal models.

2.
Molecules ; 27(4)2022 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-35208941

RESUMO

The Piper species are a recognized botanical source of a broad structural diversity of lignans and its derivatives. For the first time, Piper tectoniifolium Kunth is presented as a promising natural source of the bioactive (-)-grandisin. Phytochemical analyses of extracts from its leaves, branches and inflorescences showed the presence of the target compound in large amounts, with leaf extracts found to contain up to 52.78% in its composition. A new HPLC-DAD-UV method was developed and validated to be selective for the identification of (-)-grandisin being sensitive, linear, precise, exact, robust and with a recovery above 90%. The absolute configuration of the molecule was determined by X-ray diffraction. Despite the identification of several enantiomers in plant extracts, the major isolated substance was characterized to be the (-)-grandisin enantiomer. In vascular reactivity tests, it was shown that the grandisin purified from botanical extracts presented an endothelium-dependent vasorelaxant effect with an IC50 of 9.8 ± 1.22 µM and around 80% relaxation at 30 µM. These results suggest that P. tectoniifolium has the potential to serve as a renewable source of grandisin on a large scale and the potential to serve as template for development of new drugs for vascular diseases with emphasis on disorders related to endothelial disfunction.


Assuntos
Furanos/química , Lignanas/química , Piper/química , Extratos Vegetais/química , Furanos/metabolismo , Lignanas/metabolismo , Piper/metabolismo
3.
Cardiovasc Drugs Ther ; 35(4): 719-732, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33245463

RESUMO

PURPOSE: In the present study, the therapeutic efficacy of a selective BKCa channel opener (compound X) in the treatment of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) was investigated. METHODS: PAH was induced in male Wistar rats by a single injection of MCT. After two weeks, the MCT-treated group was divided into two groups that were either treated with compound X or vehicle. Compound X was administered daily at 28 mg/kg. Electrocardiographic, echocardiographic, and haemodynamic analyses were performed; ex vivo evaluations of pulmonary artery reactivity, right ventricle (RV) and lung histology as well as expression levels of α and ß myosin heavy chain, brain natriuretic peptide, and cytokines (TNFα and IL10) in heart tissue were performed. RESULTS: Pulmonary artery rings of the PAH group showed a lower vasodilatation response to acetylcholine, suggesting endothelial dysfunction. Compound X promoted strong vasodilation in pulmonary artery rings of both control and MCT-induced PAH rats. The untreated hypertensive rats presented remodelling of pulmonary arterioles associated with increased resistance to pulmonary flow; increased systolic pressure, hypertrophy and fibrosis of the RV; prolongation of the QT and Tpeak-Tend intervals (evaluated during electrocardiogram); increased lung and liver weights; and autonomic imbalance with predominance of sympathetic activity. On the other hand, treatment with compound X reduced pulmonary vascular remodelling, pulmonary flow resistance and RV hypertrophy and afterload. CONCLUSION: The use of a selective and potent opener to activate the BKCa channels promoted improvement of haemodynamic parameters and consequent prevention of RV maladaptive remodelling in rats with MCT-induced PAH.


Assuntos
Agonistas dos Canais de Cálcio , Canais de Potássio Ativados por Cálcio de Condutância Alta , Hipertensão Arterial Pulmonar , Quinolinas/farmacologia , Resistência Vascular/efeitos dos fármacos , Vasoconstrição/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Animais , Agonistas dos Canais de Cálcio/metabolismo , Agonistas dos Canais de Cálcio/farmacocinética , Modelos Animais de Doenças , Canais de Potássio Ativados por Cálcio de Condutância Alta/agonistas , Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , Hipertensão Arterial Pulmonar/tratamento farmacológico , Hipertensão Arterial Pulmonar/metabolismo , Hipertensão Arterial Pulmonar/fisiopatologia , Ratos , Ratos Wistar , Resultado do Tratamento , Remodelação Vascular/efeitos dos fármacos , Função Ventricular Direita/efeitos dos fármacos
4.
Steroids ; 163: 108711, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32739291

RESUMO

AIM: The present study investigated the effects of anabolic steroid (AS) excess on blood pressure regulation. METHODS: Male Wistar rats were treated with nandrolone decanoate (AS) or vehicle (CTL) for 8 or 10 weeks. Saline (1.8%) and water intake were measured in metabolic cages. Urinary volume, osmolarity, Na+ and K+ concentrations, and plasma osmolarity were measured. The autonomic balance was estimated by heart rate variability at baseline or after icv injection of losartan. Cardiac function was assessed by echocardiography and ex vivo recordings. Myocardial collagen deposition was evaluated by Picrosirius-Red staining. Vascular reactivity and wall thickness were investigated in aortic sections. Blood pressure (BP) was assessed by tail-cuff plethysmography. Angiotensin II type I receptor (AT1R), renin, and mineralocorticoid receptor (MR) mRNA expression was measured in the kidneys and whole hypothalamus. RESULTS: AS group exhibited decreased urinary volume and Na+ concentration, while urinary K+ concentration, plasma osmolarity, and renal AT1R and renin mRNA levels were increased compared to CTL (p < 0.05). Water intake was increased, and saline intake was decreased in the AS group (p < 0.01). AS group exhibited increased low-frequency/high-frequency-ratio, while it was decreased by icv injection of losartan (p < 0.05) compared to baseline. Neither cardiac function nor vascular reactivity/morphology was affected by AS excess (p > 0.05). Ultimately, BP levels were not altered by AS excess (p > 0.05). CONCLUSION: AS excess promoted hydroelectrolytic and autonomic imbalance but did not alter vascular or cardiac function/morphology.


Assuntos
Anabolizantes/farmacologia , Sistema Nervoso Autônomo/efeitos dos fármacos , Sistema Nervoso Autônomo/fisiologia , Pressão Sanguínea/efeitos dos fármacos , Decanoato de Nandrolona/farmacologia , Animais , Regulação da Expressão Gênica/efeitos dos fármacos , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Rim/efeitos dos fármacos , Rim/metabolismo , Masculino , Mineralocorticoides/genética , RNA Mensageiro/genética , Ratos , Ratos Wistar , Receptor Tipo 1 de Angiotensina/genética , Renina/genética
5.
J Cell Physiol ; 234(10): 18086-18097, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30887515

RESUMO

S17 is a clonogenic bone marrow stromal (BMS) cell line derived from mouse that has been extensively used to assess both human and murine hematopoiesis support capacity. However, very little is known about the expression of potassium ion channels and their function in cell survival and migration in these cells. Thus, the present study was designed to characterize potassium ion channels using electrophysiological and molecular biological approaches in S17 BMS cells. The whole-cell configuration of the patch clamp technique has been applied to identify potassium ion currents and reverse transcription polymerase chain reaction (RT-PCR) used to determine their molecular identities. Based on gating kinetics and pharmacological modulation of the macroscopic currents we found the presence of four functional potassium ion channels in S17 BMS cells. These include a current rapidly activated and inactivated, tetraethylammonium-sensitive, (IKV ) in most (50%) cells; a fast activated and rapidly inactivating A-type K + current (IK A -like); a delayed rectifier K + current (IK DR ) and an inward rectifier potassium current (IK IR ), found in, respectively 4.5%, 26% and 24% of these cells. RT-PCR confirmed the presence of mRNA transcripts for the alpha subunit of the corresponding functional ion channels. Additionally, functional assays were performed to investigate the importance of potassium currents in cell survival and migration. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analyses revealed a reduction in cell viability, while wound healing assays revealed reduced migration potential in cells incubated with different potassium channel blockers. In conclusion, our data suggested that potassium currents might play a role in the maintenance of overall S17 cell ionic homeostasis directly affecting cell survival and migration.


Assuntos
Movimento Celular , Células-Tronco Mesenquimais/metabolismo , Canais de Potássio/metabolismo , Potássio/metabolismo , Animais , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular , Ativação do Canal Iônico , Cinética , Potenciais da Membrana , Células-Tronco Mesenquimais/efeitos dos fármacos , Camundongos , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio/efeitos dos fármacos , Canais de Potássio/genética , Transdução de Sinais
6.
Mol Pharmacol ; 81(4): 567-77, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22241372

RESUMO

High-conductance calcium-activated potassium (Maxi-K) channels are present in smooth muscle where they regulate tone. Activation of Maxi-K channels causes smooth muscle hyperpolarization and shortening of action-potential duration, which would limit calcium entry through voltage-dependent calcium channels leading to relaxation. Although Maxi-K channels appear to indirectly mediate the relaxant effects of a number of agents, activators that bind directly to the channel with appropriate potency and pharmacological properties useful for proof-of-concept studies are not available. Most agents identified to date display significant polypharmacy that severely compromises interpretation of experimental data. In the present study, a high-throughput, functional, cell-based assay for identifying Maxi-K channel agonists was established and used to screen a large sample collection (>1.6 million compounds). On the basis of potency and selectivity, a family of tetrahydroquinolines was further characterized. Medicinal chemistry efforts afforded identification of compound X, from which its two enantiomers, Y and Z, were resolved. In in vitro assays, Z is more potent than Y as a channel activator. The same profile is observed in tissues where the ability of either agent to relax precontracted smooth muscles, via a potassium channel-dependent mechanism, is demonstrated. These data, taken together, suggest that direct activation of Maxi-K channels represents a mechanism to be explored for the potential treatment of a number of diseases associated with smooth muscle hyperexcitability.


Assuntos
Canais de Potássio Ativados por Cálcio de Condutância Alta/fisiologia , Músculo Liso/fisiologia , Animais , Células CHO , Cromatografia Líquida , Cricetinae , Cricetulus , Canais de Potássio Ativados por Cálcio de Condutância Alta/agonistas , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Relaxamento Muscular
7.
Proc Natl Acad Sci U S A ; 106(52): 22211-6, 2009 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-20007782

RESUMO

Venomous animals immobilize prey using protein toxins that act on ion channels and other targets of biological importance. Broad use of toxins for biomedical research, diagnosis, and therapy has been limited by inadequate target discrimination, for example, among ion channel subtypes. Here, a synthetic toxin is produced by a new strategy to be specific for human Kv1.3 channels, critical regulators of immune T cells. A phage display library of 11,200 de novo proteins is designed using the alpha-KTx scaffold of 31 scorpion toxin sequences known or predicted to bind to potassium channels. Mokatoxin-1 (moka1) is isolated by affinity selection on purified target. Moka1 blocks Kv1.3 at nanomolar levels that do not inhibit Kv1.1, Kv1.2, or KCa1.1. As a result, moka1 suppresses CD3/28-induced cytokine secretion by T cells without cross-reactive gastrointestinal hyperactivity. The 3D structure of moka1 rationalizes its specificity and validates the engineering approach, revealing a unique interaction surface supported on an alpha-KTx scaffold. This scaffold-based/target-biased strategy overcomes many obstacles to production of selective toxins.


Assuntos
Canal de Potássio Kv1.3/antagonistas & inibidores , Neurotoxinas/farmacologia , Peptídeos/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Venenos de Escorpião/farmacologia , Sequência de Aminoácidos , Animais , Citocinas/biossíntese , Desenho de Fármacos , Feminino , Humanos , Técnicas In Vitro , Peptídeos e Proteínas de Sinalização Intercelular , Canal de Potássio Kv1.3/genética , Ligantes , Modelos Moleculares , Dados de Sequência Molecular , Neurotoxinas/química , Neurotoxinas/genética , Oócitos/efeitos dos fármacos , Oócitos/metabolismo , Biblioteca de Peptídeos , Peptídeos/química , Bloqueadores dos Canais de Potássio/química , Engenharia de Proteínas , Ratos , Proteínas Recombinantes/antagonistas & inibidores , Proteínas Recombinantes/genética , Venenos de Escorpião/química , Venenos de Escorpião/genética , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Linfócitos T/metabolismo , Xenopus laevis
8.
BMC Immunol ; 9: 63, 2008 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-18980671

RESUMO

BACKGROUND: Ion channels are involved in the control of membrane potential (psi) in a variety of cells. The maintenance of psi in human T lymphocytes is essential for T-cell activation and was suggested to depend mostly on the voltage-gated Kv1.3 channel. Blockage of Kv1.3 inhibits cytokine production and lymphocyte proliferation in vitro and suppresses immune response in vivo. T lymphocytes are a heterogeneous cell population and the expression of Kv1.3 varies among cell subsets. Oxonol diBA-C4-(3) was used to determine psi by flow cytometry. The presence of distinct T cell subsets was evaluated by immunophenotyping techniques and the contribution of Kv1.3 channels for the maintenance of psi was investigated using selective blockers. RESULTS: The distribution of psi in T lymphocytes varied among blood donors and did not always follow a unimodal pattern. T lymphocytes were divided into CD3+/CD45RO- and CD3+/CD45RO+ subsets, whose peak channel values of psi were -58 +/- 3.6 mV and -37 +/- 4.1 mV, respectively. MgTX (specific inhibitor of Kv1.3 channels) had no significant effect in the psi of CD3+/CD45RO- subsets but depolarized CD3+/CD45RO+ cells to -27 +/- 5.1 mV. CONCLUSION: Combination of optical methods for determination of psi by flow cytometry with immuophenotyping techniques opens new possibilities for the study of ion channels in the biology of heterogeneous cell populations such as T lymphocyte subsets.


Assuntos
Subpopulações de Linfócitos/fisiologia , Potenciais da Membrana/fisiologia , Linfócitos T/fisiologia , Animais , Complexo CD3/metabolismo , Células CHO , Cricetinae , Cricetulus , Citometria de Fluxo , Humanos , Antígenos Comuns de Leucócito/metabolismo , Leucócitos Mononucleares/fisiologia , Venenos de Escorpião/farmacologia
9.
Biochemistry ; 41(24): 7781-94, 2002 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-12056910

RESUMO

The voltage-gated potassium channel, K(v)1.3, is a novel target for development of immunosuppressants. Using a functional (86)Rb(+) efflux assay, a new class of high-affinity K(v)1.3 inhibitors has been identified. The initial active in this series, 4-phenyl-4-[3-(2-methoxyphenyl)-3-oxo-2-azaprop-1-yl]cyclohexanone (PAC), which is representative of a disubstituted cyclohexyl (DSC) template, displays a K(i) of ca. 300 nM and a Hill coefficient near 2 in the flux assay and in voltage clamp recordings of K(v)1.3 channels in human T-lymphocytes. PAC displays excellent specificity as it only blocks members of the K(v)1 family of potassium channels but does not affect many other types of ion channels, receptors, or enzyme systems. Block of K(v)1.3 by DSC analogues occurs with a well-defined structure-activity relationship. Substitution at the C-1 ketone of PAC generates trans (down) and cis (up) isomer pairs. Whereas many DSC derivatives do not display selectivity in their interaction with different K(v)1.x channels, trans DSC derivatives distinguish between K(v)1.x channels based on their rates of C-type inactivation. DSC analogues reversibly inhibit the Ca(2+)-dependent pathway of T cell activation in in vitro assays. Together, these data suggest that DSC derivatives represent a new class of immunosuppressant agents and that specific interactions of trans DSC analogues with channel conformations related to C-type inactivation may permit development of selective K(v)1.3 channel inhibitors useful for the safe treatment of autoimmune diseases.


Assuntos
Cicloexanonas/farmacologia , Imunossupressores/farmacologia , Bloqueadores dos Canais de Potássio , Canais de Potássio de Abertura Dependente da Tensão da Membrana/antagonistas & inibidores , Alanina/genética , Animais , Sítios de Ligação , Células CHO , Linhagem Celular , Cricetinae , Cicloexanonas/síntese química , Cicloexanonas/metabolismo , Cobaias , Humanos , Imunossupressores/síntese química , Imunossupressores/metabolismo , Líquido Intracelular/metabolismo , Canal de Potássio Kv1.3 , Ativação Linfocitária/efeitos dos fármacos , Monoiodotirosina/metabolismo , Técnicas de Patch-Clamp , Fenilalanina/genética , Canais de Potássio/genética , Canais de Potássio/metabolismo , Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , Ratos , Venenos de Escorpião/metabolismo , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Linfócitos T/metabolismo , Transfecção , Triterpenos/metabolismo , Tirosina/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...